Rechargeable cells, such as the nickel-cadmium cells, have a relatively constant potential during discharge and can be recharged many times, thus extending their useful life. In general, any secondary or rechargeable cell contains a combination of active materials which can be electrolytically oxidized and reduced repeatedly. In rechargeable cells, reactions at both electrodes are reversible and the input of current in the appropriate direction from an outside source will reverse the discharge reaction and, in effect, recharge the electrodes.
The rechargeable cells have been used in various type devices, such as toys, calculators, radios and other types of power-operated devices. Many of the power-operated devices on the market today have been designed to accommodate cylindrical cells of the "AA", "C", and "D" size or the 9-volt rectangular cell. The cylindrical sizes have now become standard-type cell sizes having overall dimensions which can be found in various publications, such as The American National Standard Specifications For Dry Cell Batteries--ANSI C18.1-1969 published by the American National Standards Institute, Inc., New York, N.Y.
There are many different types of chargers on the market which employ standard transformer and half-wave or full-wave rectifier circuit means for providing a direct current for charging rechargeable type cells or batteries. The cell holders of the chargers are generally designed to accommodate a single size cell. Recently, cell holders have been designed which can accommodate two or more standard size cells through the use of adapters. For example, one cell holder is designed to accommodate "D" size cells and, in addition, comes equipped with a hollow "D" size shell into which a "C" size cell can be placed. The hollow shell is constructed such that the terminals of the "C" size cell are electronically contacted to terminals on the shell thereby providing the inner cell with an outer "D" size shell configuration. Thus the "C" size cell can be charged in the "D" size cell adapter.
U.S. Pat. No. 4,101,818 in the name of William T. Kelly III and Francis Stahl discloses a multi-cell battery charge that is constructed to accommodate either "D" size, "C" size or "AA" size cells, but not combinations of these size cells at the same time. The charger of this disclosure does not require any adapter for charging the various size cells.
One of the objects of this invention is to provide an improvement over the multi-cell battery charger disclosed in U.S. Pat. No. 4,101,818 by providing selective recessing of the terminal members to insure that the charger will only operate when the cells are inserted in the proper direction.
Another object of this invention is to provide a multi-cell charger that does not require any adapter for charging cylindrical "AA", "C", or "D" size cells, or standard 9-volt rectangular cells measuring about 1 inch wide by 0.7 inch thick and 1.9 inch high.
The foregoing and additional objects will become more fully apparent from the following description and the accompanying drawings.